This invention relates to a suspension rail for the carrying of hangers, especially, although not exclusively, garment hangers.
In garment manufacturing factories, in garment marshalling sheds, and garment carrying vehicles, and some other locations, rail systems are used for the suspension and conveying of garments and garment parts in large numbers. These systems use suspension rails which may be used in conjunction with drive arrangements so that the garments can be power driven from location to location. Additionally or alternatively, the systems may have rails from which the garments are suspended on their hangers for movement by manual force.
In any event, the garments are suspended by their hangers in such a manner as to friction engage the rail in that the hook of the hanger drapes over the rail and depending upon the weight of the hanger and its supported garment, so the hanger will engage the rail with a certain force. To move the hanger and its garment along the rail, a certain effort is needed to overcome the friction between the rail and the hanger, and when it is noted that as many as 1000 hangers and their garments may have to be moved at any one time, considerable effort is needed to move the garments, and accordingly it is desired that the coefficient of friction, static and dynamic, between the hangers and rail, should be as small as possible.
Heretofore, not much attention has been paid to the construction of the rail, as regards minimising friction, as it is most common for the systems to be power driven, and the rail simply has been made as robustly and cheaply as possible. Consequently, the rails of existing rail systems have tended to be of steel, with the hanger loop running directly on a track of steel. To keep the system running efficiently, the steel rails have to be lubricated from time to time, and the tracks are prone to rusting.
Secondarily, when it has to be scrapped, the steel rail does not have a good residual value.
The present invention seeks to provide a suspension rail exhibiting good friction characteristics, and which, in the preferred from makes use of aluminium in place of steel, giving the rail a better residual value than steel. It is also to be mentioned that some steel constructions may be used, and indeed steel and aluminium combinations can also be used.
According to the invention there is provided a suspension rail comprising a rail body having slide track means extending lengthwise of the rail, said slide track means being adapted to slidably support hangers thereon, wherein the slide track means comprises two parallel tracks of low friction plastics held in or by the rail body and spaced by the rail body, so that a hanger suspended on the rail contacts the rail only at the two tracks.
The use of low friction plastics rod means that lubrication will not be required, overcoming the disadvantage of the known steel rails. However, it is desired that the plastics material should be of high wear resistance, so that replacement is not required too frequently, if at all.
It has been found that the plastic material sold by Du Pont under the name Delrin (registered trade mark) is particularly suitable in that it has the following characteristics
The tests were conducted at speed 0.5 m/s and at a load of 10N
The steel type was as above. Speed 0.084 m/s; pressure 0.624 MPs
The reason for testing Delrin against steel and against itself is that the hangers typically will be of steel or plastics material.
The above figures illustrate a material which is excellent for this invention, but it is to be mentioned that the invention is not to be considered as limited to this material.
It is preferred that the two tracks be separate, discrete rods in that by virtue of using two discrete tracks, these tracks can be of a small size and of simple cross section, including circular or approximating to circular, but other shapes, such as triangular, as referred to herein are particularly effective in having particular advantage. Indeed, tracks of or approximating triangular shape are particularly preferred, in that a corner of a triangular shape can project beyond the rail body further than say circular tracks, and the wide base part can be effectively locked in grooves in the rail body.
The provision of two separate and small sized rods is of importance in that it has been found that the above plastic which I have been able to identify as being particularly suitable for the purpose is very expensive, and part of this invention is to achieve low friction/low wear suspension, but to keep the cost of the rail to a competitive level.
Typically, although not limiting, the rods of plastic will be of the order of ⅚ mm in diameter or maximum dimension.
In a preferred arrangement, the rods are initially held in grooves in the body in a somewhat loose fashion and then the rods are anchored in the grooves by deforming (e.g. crimping) the material forming the sides of the grooves onto the tracks. The rail body may be specially configured to enable this to be done. The configuring may be done by design of the extrusion shape, when the body, as is preferred, is a one-piece extrusion.
In a preferred arrangement, the rail body is entirely or mostly of aluminium extrusion or steel, and it may be in one or more parts.
The use of aluminium provides the advantage mentioned above that the residual value of the rail is greater than steel in that aluminium can be more readily re-processed.
The rods may be placed in grooves by being sprung or slid into the grooves, or in another arrangement, where the deforming is not needed, they may held by so designing the rail body that the rods can be placed in the body and then are clamped in position.
In such other arrangement, the rods may be held in position after mounting of a part of the rail in its in use position in the factory or other location, followed by fitting of the rods, which may be in long lengths or short lengths, followed by fitting a clamping part or parts of the rail which clamp the rods in position. Secure holding of the rods is important, as they will not always be arranged in straight configuration, in that these suspension rails are often required to curve in horizontal and vertical planes. When the rails are curved, there is a tendency for circular tracks to spring out of the grooves.
The rails used in any one factory or storage or marshalling shed, may run to many hundreds of meters, and so although long lengths of rod may be used, there will inevitably be joints or junctions (for example at switch points as explained herein) in the rods of the respective tracks. Where there are joints, in one arrangement, the joints of one of the tracks are staggered longitudinally of the joints in the other track.
According to a preferred form of the invention however, the suspension rail comprises a joint or junction, preferably enabling the plastic rods to expand with temperature increase, and at such joint or junction, the ends of rod sections are covered by a jumper rail section which overlies rod ends, providing a ramp over which the hangers travel as they are moved along the rail and over the joint or junction.
Preferably, when the jumper rail section is at a joint, the aligned ends of the rod sections in the respective grooves are spaced to allow for thermal expansion, and the jumper rail section has tongues which are engaged in the body grooves between the aligned ends of the rod sections, which are spaced sufficient to accommodate the expansion and the tongues.
At junctions, for example at switch locations, rail sections may be coupled by connecting blocks, and each connecting block may have an integral ramp for the purposes aforesaid.
At a switch section, a switch length of rail may be pivoted to a first main length of rail, so as to be selectively aligned, manually or automatically, with either of at least two further main lengths of rail, whereby the hangers can travel from the first length of rail to the second or third length of rail and vice versa.
Although in the preferred embodiment, the body is a one piece aluminium extrusion, in another embodiment the rail comprises an extruded section defining spaced parallel seats for the rods of the respective tracks, the section also having a bridge portion extending between the seats, said bridge portion being adapted to receive, preferably by push fitting, plastic clamping sections or plugs which have clamping edges which engage and clamp the rods when the clamping sections or plugs are fitted to the section defining the seats, after the rods are located on said seats.
Many configurations of rail for holding the rods are possible.